An attempt to inactivate mimosine of Leucaena leucocephala by mineral supplementation for feeding to ruminants

Abstract

In an in vitro study an attempt was made to examine the effect of iron as ferric chloride at the 0, 4 and 8 g kg −1 level and copper as cupric sulphate at 0, 10, 25, 50 and 100 mg kg −1 of dry matter (DM) on ruminal mimosine degradation and fermentation of Leucaena leucocephala leaf meal during 24 h incubation. Further, short-term (10 days) in vivo studies were conducted on feeding of copper sulphate treated (Cu 10 mg kg −1 DM) leucaena to cross-bred calves. Iron at the 8 g kg −1 level and copper at the 10 mg kg −1 level and onwards decreased ammonia nitrogen in the rumen liquor in vitro. However total nitrogen, microbial protein synthesis, total volatile fatty acids and their individual proportions remained unaffected due to these trace minerals. In vitro mimosine degradation was reduced (P < 0.05) from 87.41 to 82.62 at an iron level of 4 g kg −1 or above. A copper level of 10 mg kg −1 and above significantly (P < 0.05) decreased mimosine degradation (from 85.75 to 78.80). Apparently DM intake, DM digestibility, organic matter digestibility increased by 0.68 % units per 100 kg live weight, 3.12 % units and 2.46 % units, respectively, in calves fed copper treated leucaena. Mimosine intake was higher in the copper treated group (0.512 g as compared with 0.319 g per kg live weight) but the 3,4-DHP excretion mimosine ingestion ratio was 0.345 as compared with 0.412 in the untreated group. Hence, in vitro and in vivo studies revealed reduced mimosine degradation due to copper supplementation of the leucaena diet.